Measurement of the atmospheric νμ flux with six detection units of KM3NeT/ORCA

Abstract

A measurement of the atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ flux with energies between 1 and 100 GeV is presented. The measurement has been performed using data taken with the first six detection units of the KM3NeT/ORCA detector, referred to as ORCA6. The data were collected between January 2020 and November 2021 and correspond to 510 days of livetime, with a total exposure of 433 kton$·$years. Using machine learning classification, 3894 neutrino candidate events have been selected with an atmospheric muon contamination of less than 1$\%$. The atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ energy spectrum is derived using an unfolding procedure and the impact of systematic uncertainties is estimated. The atmospheric ${\nu }_{\mu }+{\overline{\nu }}_{\mu }$ flux measured using the ORCA6 configuration is in agreement with the values measured by other experiments.